Although the following description refers generally to ladders, no limitation is intended thereby. Any related device including, but not necessarily limited to, step ladders, extension ladders, trestles, work platforms, scaffolding, sawhorses, workbenches and other work tables etc having leg members (including picnic tables and the like), wherein such device is normally required to be set on level ground to provide a level step, platform or other level work area in order to be safely used, is also contemplated. The invention may also be employed in other circumstances where extendable legs or their equivalent are required, whether or not a levelling of the device itself is paramount or even achieved. For example, it is well known to use so-called strutting devices (ie a single leg member) which can be extended and locked in such extended position to provide temporary support, for example to jack up beams or sheets of cladding during construction. Such devices would also benefit from use of the invention therein.
Of necessity, ladders are used on a variety of surfaces and in many instances the ground or surface on which they are used is uneven, sloped or stepped. Conventional ladders having fixed length legs are rendered unsafe by even the slightest unevenness, particularly where longer lengths of ladder are involved, as the weight loading in relation to the centre of gravity is paramount. In other words the higher one goes on a non level ladder, the greater the danger there is of overbalancing. In the past it has been necessary to chock up one or more legs of a ladder to overcome any unevenness in the terrain. However, this also renders the use of the ladder relatively unsafe as the chock itself may move, or the ladder can otherwise slip off it, with disastrous consequences.
In order to overcome the inherent lack of safety and other difficulties in using blocks and chocks etc, attempts have been made to produce so-called ladder levelling devices. Conventional ladder levellers are usually add-on devices which can be expensive and cumbersome. In any event, to safely level a ladder using previously known devices, it is generally necessary that the person intending to use the ladder do so in a standing position, whilst operating the relevant mechanism, and at the same time sighting a gauge or level and maintaining the overall stability of the ladder. In many instances this can be a complex task, given the degree of adjustment required for known ladder levelling devices.
It would therefore be extremely advantageous to provide a simple means of levelling a ladder, which is relatively easy to use and which is itself extremely safe to use.